Bander machines for drugs capsules are known comprising a conveyor belt able to transfer said capsules from a first feeding station to a second gelatin welding station and, subsequently, it carries the capsules from said second to a third draw station therefor. Said conveyor belt is usually constituted by a plurality of metallic trays disposed in sequence and parallel each other; each tray has a plurality of pits each of which is adapted to house with precision a capsule.
In the known machines it is necessary to simultaneously feed the capsule in the pits of a unique tray, therefore it is necessary for said trays to be sufficiently long to minimize the feeding times. This peculiarity involves a deflection which can reach the size of some millimeters and which can cause very intense jerks in the middle part of the trays during the subsequent movements thereof.
Further, a feeding system like that above disclosed, involves a particularly wide breadthways sizing of the feeding and carrying structures and, therefore, of the bander machine. This makes it difficult to establish bander machines fitted with two or more conveyor belts, therefore the known bander machines are fitted with a unique conveyor belt with the consequent disadvantage of being obliged to stop the treatment process when the machine is subjected to a failure downstream of the first or the second station.
Other disadvantages of the known machines can be noted in the devices for welding said annular seals on the capsules. Particularly these devices are constituted by a roller operated by an electric motor; said roller being partially and longitudinally immersed in said gelatin to bring it from a liquid gelatin tank to the capsules housed in the pits of the trays.
The optimal viscosity values for the welding of liquid gelatin on the capsules depend on the temperature; the gelatin housed in a tank inclines to cool and to loose the optimal viscosity values; for this reason it is necessary to continuously control the viscosity degree and, when necessary, to stop the machine to reset the correct viscosity values of the gelatin. Besides the known machines accomplish the hardening process for the seal after the fall in bulk of the capsules in a zone of the machine downstream of the second station and this causes a possible damaging of the seal not yet hardened.
The known machines have difficulty in flushing the structures adapted for receiving the capsules and the structures adapted for welding liquid gelatin on said capsules. Further, in the known machines, the capsules are disposed in said pits without a specific orientation. Since the edges of the capsules are not exactly on the middle of the longitudinal dimension of said capsules, the welding of the seal in the sealing zone between the covers and the bottoms is not sure.
Finally, the known machines need many movements of the capsules's feeding device able to feed said capsules on the pits, therefore the treatment times become long.